Detecting method and apparatus of specific substance

ABSTRACT

A method and an apparatus for detecting the existence of a specific substance in an article to be inspected in which an electromagnetic wave having energy in the vicinity of transition energy between spin states of an atomic nucleus applied with energy splitting due to electrostatic interaction between said atomic nucleus in the specific substance and an electric field in the substance which is peculiar to said specific substance is irradiated to the article to be inspected, thereby detecting transition between said spin states.

TECHNICAL FIELD

The present invention relates to a method and an apparatus for detectinga specific substance included in an article to be inspected togetherwith other substances in a non-destructive manner, and more particularlyto a method and an apparatus for detecting a specific substance whichare best suited for detecting forbidden substances having no definiteconfiguration such as awakening drugs, narcotics or plastic bombs hiddenin a baggage that have been difficult to be detected by a conventionalX-ray inspection apparatus only.

BACKGROUND ART

An X-ray inspection system which is an apparatus for inspecting aircraftpassenger's baggages and dangerous articles in transport freights, etc.has been composed of an X-ray generating unit, an X-ray transmittingslit, a belt conveyor for moving articles to be inspected, a line sensordetecting the X-ray that has transmitted through said articles to beinspected, a monitor television and the like which displays atransmitted image. With such a composition, metallic swords, small armsand the like having a strong X-ray scattering intensity can be detectedas a clear image on a television monitor, which is serviceable forpreventing aircraft hijact from occurring.

A prior art of this sort has been disclosed in the Japanese PatentApplication Laid-Open Number SHO61-189447 for instance.

With abovesaid prior art, it is difficult to detect weapons anddangerous articles that contain no metal as composing elements. Inaddition, there has been such a problem that forbidden substances havingno definite configuration such as awakening drugs, narcotics or plasticbombs are overlooked completely.

Further, there have been such problems that, it is difficult to obtainan information in the depth direction in the articles to be inspectedbecause said proir art utilizes a transmitted image of an X-ray, openinginspection and removal of suspected articles that are not shown clearlybut suspencted to be forbidden substances cannot be conducted in a shorttime, and abovementioned operation itself involves a risk.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a method and anapparatus for detecting a specific substance included in an article tobe inspected together with other substances in a non-destructive manner.

It is another object of the present invention to provide a new apparatusfor detecting the existence of forbidden substances composed of anorganic substance or an inorganic substance in a liquid form, a powderform or a soft clay form (hereinafter referred to as a plastic form)which has been difficult to be detected with a conventional X-raytransmitting inspection apparatus, thus securing safe transportation byaircraft and also providing means of performing forbidden substanceremoval operation quickly and safely.

The abovementioned object may be achieved by detecting forbiddensubstance such as plastic bombs through the detection of nuclearquadrupole resonance which is peculiar to a molecular structure ofcomposing element instead of the configuration of the composing element.

Further, abovesaid another object of the present invention may beachieved by installing additionally a radio wave generating unit, a coilfor detecting radio wave irradiation and a radio wave absorptionmeasuring unit onto a conventional perspective type X-ray inspectionapparatus, and performing comprehensive detection by configurationinformation and material information of forbidden substances.

The nuclear quadrupole resonance occurs when a radio wave is irradiatedonto an atomic nucleus having nuclear spin of 1 or more and nuclearquadrupole moment not zero. Further, since the resonance frequency has avalue peculiar to a chemical bonding state of the atomic nucleus, theresonance frequency differs if the molecules containing the atomicnucleus are different even if the atomic nucleus type is the same. Mostof explosive substances include introgen 14 (spin: 1, nuclear quadrupolemoment: +0.016 barn), chlorine 35 (nuclear spin: 3/2, nuclear quadrupolemoment: -0.079 barn) and the like, and these atomic nuclei give rise tonuclear quadrupole resonance. Thus, it is possible to judge theexistence of a forbidden substance in the article to be inspected andfurther to identify the type of the forbidden substance by observingresonance absorption of these atomic nuclei.

A generally well-known apparatus which is constituted basically with aradio wave generating unit, a coil for detecting radio wave irradiationand a radio wave absorption measuring equipment may be used for theapparatus for observing resonance absorption.

That is, abovesaid radio wave generating unit generates a radio wave inan absorption band peculiar to a forbidden substance composed of anorganic substance or an inorganic substance, and the coil for radio waveirradiation detection irradiates the radio wave generated by said radiowave generating unit to an article to be inspected with high efficiency.Then, it is inspected with the coil for radio wave irradiation detectionand the radio wave absorption measuring equipment whether abovementionedirradiated radio wave has been abosrbed or not by the article to beinspected. When absorption occurs, it means that a forbidden substancewhich corresponds to the relevant radio wave absorption band has beendetected. Since forbidden substances in a liquid form, a powder form ora plastic form composed of an organic substance or an inorganicsubstance have peculiar radio wave absorption bands, respectively, radiowave absorption peculiar to respective forbidden substances can bedetected even if the forbidden substances contained in the article to beinspected are not single but variety of mixtures by performingrespective operations of the above-described radio wave generating unit,coil for radio wave irradiation detection and radio wave absorptionmeasuring equipment repeatedly while varying the frequency of the radiowave generated from the radio wave generating unit. Thus, it is possibleto detect all of specific forbidden substances without missing. On theother hand, when forbidden substances in a liquid form, a powder form ora plastic form composed of an organic substance or an inorganicsubstance are sealed with a radio wave reflecting material, it isdifficult to detect these forbidden substances by radio wave absorption.However, since all of the radio wave reflecting materials are metallicmaterials, they can be detected easily by a conventional X-rayinspection apparatus.

Accordingly, it is possible to increase forbidden substance inspectioncapability by combining the nuclear quadrupole resonance observationapparatus and the X-ray inspection apparatus together. That is, metallicforbidden substances are detected by an X-ray inspection apparatus, andnon-metallic forbidden substances are detected by a radio waveinspection apparatus consisting of a radio wave generating unit, a radiowave irradiation detection coil and a radio wave absorption measuringequipment in the forbidden substance inspection apparatus according tothe present invention. Accordingly, it is possible to detect all theforbidden substances complementarily without missing by means of X-rayand radio wave inspection apparatus irrespective of the quality, theconfiguration and the composition of the forbidden substances.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6 and FIG. 7 are blockdiagrams showing respective different embodiments of a detectingapparatus by radio wave irradiation according to the present invention;

FIG. 8 is a typical view of a coil having a configuration which iseffective in Embodiments 1 through 7;

FIG. 9 is a curve diagram showing signal intensity of nuclear quadrupoleresonance absorption which is measured with a coil shown in FIG. 8 and aHelmholtz coil;

FIG. 10 is a diagram for explaining an embodiment of a dangerous articleinspection apparatus in which radio wave irradiation detection and X-raydetection are combined together according to the present invention;

FIG. 11 is a diagram for explaining an embodiment in which a pluralityof irradiation coils are arranged;

FIG. 12 is a diagram for explaining an embodiment in which irradiationdetecting coils are arranged on a flexible insulating film;

FIG. 13 is an explanatory view showing an embodiment in which nuclearquadrupole resonance radio wave absorption is utilized;

FIG. 14 is a curve diagram showing the result of measurement of freeinduction decay signal of chlorine 35 nuclear quadrupole reasonanceabsorption of potassium chlorate dummy dangerous article in a suit case;and

FIG. 15 is an explanatory view of an embodiment in which nuclearmagnetic resonance radio wave absorption is utilized.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

An embodiment of the present invention will be described hereafter withreference to FIG. 1.

In FIG. 1, a detecting apparatus consists of a controller 5 whichcontrols the whole operation, a setting unit 4 which sets the frequencyand the sweep sequence of an electromagnetic wave irradiated to anarticle to be inspected 1 by the controller 5, an electromagnetic waveirradiation unit 3 which creates and emits a high frequency pulseaccording to those that have been set by the setting unit 4, a spintransition detector 2 which detects spin transition of the article to beinspected 1 by nuclear quadrupole resonance produced by theelectromagnetic wave from the electromagnetic wave irradiation unit 3and so forth. The electromagnetic wave irradiation unit 3 and the spintransition detector 2 may be constructed to include a transmission coiland a reception coil, respectively, or a coil for both transmission andreception may be provided on the side of the irradiation unit 3. Theelectromagnetic wave irradiation unit 3 irradiates an electromagneticwave corresponding to the spin transition of the detected article in thearticle to be inspected 1. Setting an sweeping, etc. of the irradiatingfrequency is performed with the frequency setting unit 4. Theirradiation unit 3 is capable of irradiating electromagnetic wavescovering the frequency range of several KHz to several hundred GHz. Forexample, when an explosive substance containing nitrogen 14 nucleus inthe article to be inspected 1 is tried to be detected, frequency sweepis performed on electromagnetic waves covering the radio frequencyregion corresponding to nitrogen 14 nucleus spin transition (the rangeof about 300 KHz to 8 MHz) by sending a command to the frequency settingunit 4 from the controller 5, and the electromagnetic waves areirradiated onto the article to be inspected from the electromagneticwave irradiation unit 3 and the spin transition of nitrogen 14 nucleusis detected using the spin transition detector 2, thus enabling todetect the explosive substance. The inspection result is displayed on adisplay 2'.

Embodiment 2

Next, a more concrete embodiment of the present invention will bedescribed more in detail with reference to FIG. 2.

In FIG. 2, a probe coil 6 is connected to a radio wave oscillator anddetector 7. It is possible to set the frequency of a radio wave magneticfield emitted externally by the probe coil 6 to a desired value byvarying the capacity of a capacitor by means of a frequency controller8. Further, an oscillating voltage detected in said radio waveoscillator and detector 7 is amplified by an amplifier 9 and displayedon a signal display 10. The set frequency in said frequency controller 8is made to accord with nuclear quadrupole resonance frequency ofnitrogen 14 nucleus, for example, under a chemical structure peculiar tothe explosive substance in advance. Then, when the probe coil 6 is movedaround the article to be inspected 1, the conductance of a turningcircuit of the radio wave oscillator and detector 7 including the probecoil varies in accordance with a real component (absorption component)of the magnetic susceptibility of nitrogen 14 in an explosive substance11. With such variation, the oscillation voltage of the radio waveoscillator and detector 7 also varies. The oscillation voltage isamplified by the amplifier 9, and the variation of the oscillationvoltage is detected and displayed by the signal display 10, thus makingit possible to detect the existence of the explosive substance 11.

Embodiment 3

Next, another embodiment of the present invention will be explained withreference to FIG. 3. In FIG. 3, frequency sweep is performed on theradio wave in the probe coil 6 and the radio wave oscillator anddetector 7 by means of the frequency controller 8, and the sweepfrequency is frequency-modulated with a frequency of approximately 200Hz by means of an FM modulator 12. Further, among oscillation voltagesdetected in the radio wave oscillator and detector 7, abovementionedfrequency is detected and amplified by a lock-in amplifier 13, and thesignal is read by the signal display 10. According to the presentembodiment, the frequency-modulated wave is detected as a firstderivative of the absorption line, and the modulated frequency componentis lock-in amplified. Thus, detection with higher sensitivity ispossible as compared with the embodiment explained with reference toFIG. 2.

High sensitivity achieved by modulation is obtainable not only byfreuqency modulation as explained in the embodiment with reference toFIG. 3, but also by modulating the amplitude (intensity) of the radiowave with a frequency of about 200 Hz. That is, since the amplitudevariation becomes big at the resonance point only, the noise iseliminated thereby to increase the sensitivity if only the modulatedfrequency component only is detected. Further more, it is also possibleto produce effects similar to the abovesaid embodiment in which theradio wave is frequency-modulated by utilizing Zeeman modulation inwhich an alternating magnetic field of about 200 Hz of several G toseveral tens of G is applied, thereby to obtain high sensitivity. Inthis case, high sensitivity is easily achieved only by adding analternating magnetic field application coil to the apparatus compositionshown in FIG. 3. It is only required that the frequency of thealternating magnetic field falls within the range of several tens Hz toseveral KHz.

Further, by providng a circuit heretofore known which detects thereactance variation in a radio wave circuit, said reactance variationcaused by an imaginary component (dispersion component) of the magneticsusceptibility of nitrogen 14 can be detected. With this, it is possibleto forecast the existence of the explosive substance 11. This detectingmethod is particularly effective when absorption of radio wave energy bynitrogen 14 is saturated easily.

Embodiment 4

Furthermore, a device that has such a construction that a pulse radiowave generator and a high speed detector which can follow the phenomenain the radio wave region are connected to the probe coil may also beused. An embodiment of the apparatus composition in this case will beexplained with reference to FIG. 4. The radio wave having a frequencypeculiar to a specific substance generated by a reference oscillator 14is modulated by a method heretofore known into signal high frequencypulses or a pulse train consisting of a plurality of high frequencypulses controlled in time and/or in phase by a pulse gate 15. Thiscontrol sequency is set in the controller 5 in advance. These highfrequency pulses or pulse train are amplified by a power amplifier 16 tosuch a power level that can induce spin transition of the explosivesubstance 11 in the article to be inspected 1, and is irradiated to thearticle to be inspected 1 efficiently by means of an irradiation coil17.

In case of single high frequency pulses, the explosive substance 11 canbe detected by detecting free induction decay caused by nitrogen 14after the high freuqnecy pulse is cut off.

However, the free induction decay signal of nitrogen 14 nucleuscontained in the explosive substance 11 has a feeble intensity ofseveral μV to several tens μV and has a life only from several μ secondsto several tens m seconds. Therefore, it is required that a detectionsystem such as a pre-amplifier 18 and a phase detector 19 has a shortdead time and low noise characteristics. On the other hand, in case aplurality of high frequency pulses are used, the requirement for thedead time for the detection system can be relieved appreciably. Forexample, when a 180° pulse is irradiated after the elapse of τ secondsfollowing to a 90° pulse (a pulse rotating the nuclear spin by 90°), aspin echo is produced after 2τ seconds and the free induction decaysignal is induced for reimaging. Accordingly, measurement may be madewithout deteriorating the sensitivity even if the dead time of thedetection system is about τ seconds by measuring the free inductiondecay signal after pulse irradiation for the second time. Although acase in which two pulses "90°-τ-180°" are utilized was shown in theabove example, it is possible to detect nuclear quadrupole resonance ofnitrogen 14 nucleus in the explosive substance 11 by using variety ofpulse trains heretofore known other than the above case. The advantageof using a pulse radio wave exists in such a point that a radio wave ofhigh intensity, viz., large amplitude cna be irradiated to the articleto be inspected 1. In short, since the radio wave intensity is high,high sensitivity may be aimed at, and at the same time, it is possibleto detect the explosive substance 11 that is located at a deep positionin the article to be inspected 1.

Embodiment 5

In those examples that have been heretofore described, nuclearquadrupole resonance of nitrogen 14 in the explosive substance 11 isconfirmed by detecting the variation of spin magnetic susceptibility ofnitrogen 14 nucleus attendance upon this resonance. However, otherdetecting methods which can confirm that above-described resonance hashappened may be utilized, too. Among them, there is a nuclearquadrupole-nuclear magnetic double resonance method utilizing a levelcrossing method as one of useful methods. In this method, when nuclearquadrupole resonance is performed after magnetization process by Zeemansplitting of nuclear sipn in the magnetic field, thermal energy movesfrom nitrogen 14 which has transitted to high energy state by thenuclear quadrupole resonance to other proximity atomic nucleus withZeeman splitting in a width corresponding to the transit energy, thusrelieving magnetization of the atomic nucleus. The variation of thenuclear magnetic resonance signal attended by relief of magnetization ofthis proximity atomic nucleus is detected. This proximity atomic nucleusis a proton in many cases, and it is possible to make the nuclearmagnetic resonance frequency of the proton higher than the nuclearquadrupole resonance frequency of nitrogen 14 by increasing Zeemansplitting energy of said proton adiabatically after above-describedenergy transfer has occurred. Since the detected photon energy can beincreased, the detection sensitivity is improved. It is needless to saythat atomic nuclei other than a proton may be used as abovesaidproximity atomic nucleus.

An embodiment of an apparatus composition for a double resonance methodwill be explained in detail to some extent with reference to FIG. 5. Inthe present embodiment, the level crossing method is executed bymagnetization and demagnetization process with a d.c. magnetic field byhelmholtz coils 26 arranged around the article to be inspected 1. Thedetection of the explosive substance 11 in the article to be inspected 1can be performed in steps of procedure described hereunder in accordancewith the control by the controller 5. In this example, the steps ofprocedure will be explained with a case in which the explosive substance11 in the article to be inspected 1 contains nitrogen 14 nucleus and aproton is contained in Hs proximity, but quite the same steps ofprocedure can also be adopted in case chlorine 35 nucleus is selected asthe nucleus for detecting nuclear quadrupole resonance so as to detectan explosive substance of chloric acid group. Also, nuclei other thanproton such as fluorine 19 nucleus is possible as a nucleus fordetecting a nuclear magnetic resonance signal.

Now, the article to be inspected 1 is first disposed at the centralportion of the Helmholtz coil 26. Then, a d.c. current is applied to theHelmholtz coil 26 by a magnetization/demangetization power source 24 soas to excite the explosive substance 11 contained in the article to beinspected 1, whereby to produce Zeeman splitting of the proton containedtherein. With this, magnetization of proton is created in the explosivesubstance 11. Since magnetization by proton takes time, it is requiredto hold this d.c. magnetic field for the time several times as long as aspin-lattice relaxation time T₁ of the proton in order to generate themagnetization sufficiently. Next, a d.c. current applied frommagnetization/demagnetization power source 24 is made to zero in a shortperiod of time (within a sufficiently short time as compared with thespin-lattice relaxation time T₁ of the proton in the explosive substance11). For this purpose, it is required that a magnetic energy absorbingcircuit composed of a capacitor and the like is contained internally inthe magnetization/demagnetization power source 24. Magnetization of theproton contained in the explosive substance 11 in the article to beinspected 1 is attenuated with a time constant of zero magnetic fieldrelaxation time T_(1d) because the external magnetic field has becomezero. Since it is necessary to produce level crossing before theattenuation progresses too far, an electromagnetic wave corresponding tonuclear quadrupole transition of the nitrogen 14 nucleus in the articleto be inspected 1 is created with a frequency synthesizer 22 andsupplied to an irradiation coil 25 from a wide band power amplifier 23so as to irradiate the article to be inspected 1, thereby to generatenuclear quadrupole resonance of the nitrogen 14 nucleus within a shortertime than T_(1d) after demagnetization of the d.c. magnetic field. Then,a d.c. magnetic field is regenerated by the helmholtz coil 26 from themagnetization/demagnetization power source 24, thereby to produce Zeemansplitting of the proton contained in the explosive substance in thearticle to be inspected 1. The Zeeman splitting width of the protonproduced during magnetization process varies in proportion to theintensity of the applied magnetic field. Therefore, when the photonenergy of the nuclear quadrupole transition electromagnetic waveirradiated to and absorbed by the nitrogen 14 nucleus in the explosivesubstnace 11 under the zero d.c. magnetic field state accords with theZeeman splitting width of the proton, there is a time in whichmagnetization of the proton is reduced, that is, so-called levelcrossing is occurred. When this level crossing is produce, energymigration from the nitrogen 14 reservoir to the proton system isproduced, and proton magnetization is reduced rapidly. It is possible tomeasure and detect such reduction of proton magnetization with a nuclearmagnetic resonance type spectrometer consisting of atransmission-reception coil 27, a transmitter 28, a pre-amplifier 18, areceiver 29 and an integrator 30, and the nuclear quadrupole resonanceof the nitrogen 14 nucleus in the explosive substance 11 can be detectedas reduction of proton magnetization.

In the case of the embodiment shown in FIG. 5, magnetization anddemagnetization of the d.c. magnetic field was performed by means ofswitching the helmholtz coil 26, but no hindrance is caused at all onlevel crossing even if magnetization and demagnetization are performedby putting the article to be inspected 1 in and out the d.c. magneticfield in place of the switching described above. Either a permanentmagnet or an electromagnet may be used as the d.c. magnetic fieldadopted in this case. However, uniformity of the magnetic field whichcan detect a nuclear magnetic resonance signal of the proton over thespace region occupied by the article to be inspected 1 is required.

In practical detection of an explosive substance, above-described stepsof procedure are repeated while sweeping the frequency of the nitrogen14 nucleus irradiation electromagnetic wave using the controller 5 andthe frequency synthesizer 22.

Embodiment 6

Next, still another embodiment will be described with reference to FIG.6. In the embodiments described with reference to FIG. 2 and FIG. 3, theprobe coil 6 and the radio wave circuit portion appendant thereto areformed in one body, and the whole unit is moved with respect to thearticle to be inspected 1 so as to detect the explosive substance 11. Onthe other hand, in the embodiment shown in FIG. 6, a part (referred toas probe 31) of the probe coil and the other radio wave circuit portion(referred to as the main body 32) are separated from each other, andboth are connected with a bendable cable 33. The main body 32 is fixedor semi-fixed, and only the probe 31 is moved in the neighbourhood ofthe article to be inspected 1 in detecting operation of the explosivesubstance 11. Since handling of the probe 31 is easy in the presentembodiment, detailed detecting operation can be performed simply on thearticle to be inspected 1. Furthermore, it is also possible to insertthe probe 31 into the article to be inspected 1 as occasion demands.Also, there is such an advantage that the operation efficiency is notlowered even if a large-sized radio wave oscillator is employed.

Embodiment 7

FIG. 7 shows still another embodiment. In the present embodiment, theprobe coil 6 has almost the same size as the article to be inspected 1,and the radio wave can be applied to almost the whole article to beinspected 1 at a time. In the present embodiment, it is not possible tolocate the explosive substance 11 in the article to be inspected 1, butexposure of the article to be inspected 1 containing the explosivesubstance 11 can be done easily in a short period of time.

The radio wave used in the above-described embodiment can penetrateinside without breaking the article to be inspected 1. Thus, it ispossible to detect even the explosive substance 11 hidden inside thearticle to be inspected 1. Further, in the detecting method of thepresent invention, the existence of the explosive substance 11 isdetected not by the configuration of the explosive substance 11, but bythe chemical structure itself thereof. Therefore, even an explosivesubstance 11 which can take any configuration such as a plastic bombwill never to overlooked. Furthermore, such procedures of analysis thatthe article to be inspected 1 is destructed or a part thereof it pickedup are not required. There is also such an advantage that the risk onhuman organism and other organisms is much less as compared with otherdetecting methods in which X-ray and the like are used.

According to such a method, it is possible to detect in anon-destructive manner not only an explosive substance 11 containingnitrogen 14, but also any substance containing an atomic nucleus whichproduces nuclear quadrupole resonance.

Embodiment 8

In the above-described Embodiments 1 through 7, the coil configrationfor radio wave irradiation and detection has not been limitedspecifically. That is, any coil configuration may be taken for the probecoil 6 in FIG. 2, FIG. 3 and FIG. 7, the irradiation coil 17 in FIG. 4,the irradiation coil 25 and the Helmholtz coil 26 in FIG. 5, and theprobe coil 31 in FIG. 6, but a solenoid coil or a Helmbhotz coil isillustrated in FIG. 2 through FIG. 7.

In case of detecting a dangerous article with high sensitivity, however,a coil configuration which irradiates a radio wave efficiently anddetects radio wave absorption efficiently is required.

FIG. 8 shows two pieces of spiral coils 34 disposed opposedly to eachother as the coil for highly efficient irradiation detection. Theresults of detecting nuclear quadrupole resonance absorption ofrespective articles to be inspected with these opposedly disposed spiralcoils 34 and a Helmholtz coil are shown in FIG. 9. As shown in FIG. 9,the signal intensity 36 detected by the opposedly disposed spiral coilshas a bigger value than the signal intensity detected by the hemholtzcoil, which shows that the spiral coils 34 are more sensitive than theHelmholtz coil. Moreover, as it is apparent from FIG. 9, signalattenuation is small even if the distance between coils is increased. Itis realized from these results that the spiral coils 34 are effecive todetect a dangerous article located in a large-sized baggage and at aposition apart from the coils.

The spiral coils 34 are also effective when a dangerous article isdetected with a signal coil as shown in FIG. 2.

Furthermore, a spiral coil in a signal layer is shown in FIG. 8, but amultilayer spiral coil may be adopted, too.

Next, a dangerous article detecting apparatus in which a nuclearquadrupole resonance detecting apparatus according to the presentinvention and an X-ray detecting apparatus are combined.

FIG. 10 is a diagram for explaining a ninth embodiment of a dangerousarticle detecting apparatus of the present invention, FIG. 11 is adiagram for explaining a tenth embodiment in which a plurality ofirradiation coils are arranged, FIG. 12 is a diagram for explaining aneleventh embodiment of the present invention in which irradiation coilsare arranged on a flexible insulating film, FIG. 13 is an explanatorydiagram of a twelfth embodiment of the present invention utilizingnuclear quadrupole resonance radio wave absorption, FIG. 14 shows theresults of measurement of free induction decay signal of chlorine 35nuclear quadrupole resonance absorption of potassium chlorate dummydangerous article in a suit case, and FIG. 15 is an explanatory diagramof a thirteenth embodiment of the present invention utilizing nuclearmagnetic resonance radio wave absorption.

Embodiment 9

The ninth embodiment shown in FIG. 10 has such a composition that aradio wave generating unit 101, a radio wave irradiation detecting coil102 and a radio wave absorption measuring equipment 103 are installedadditionally to a fluoroscopic inspection apparatus consisting of anX-ray generator 104, an X-ray transmitting slit 105, a jig 106 formoving an article to be inspected, an X-ray detecting sensor 107 and amonitor 108. A metallic dangerous article in an article to be inspected109, such as a small weapon and an explosive dangerous article sealed ina steel pipe, etc. has a remarkably high X-ray scattering intensity.Therefore, it is possible to detect such a dangerous article easily fromthe configuration thereof with the monitor 108. On the other hand, whenan explosive dangerous article composed of an organic substance or aninorganic substance in liquid form, powder form or plastic form having alow X-ray scattering intensity is contained in said article to beinspected 109, it is difficult to detect such an explosive dangerousarticle as a clear image on the monitor 8 with said fluoroscopicinspection apparatus. In this case, the existence and the degree of aspecific radio wave absorpiton which is peculiar to said dangerousartricle may be detected by the radio wave generating unit 101, theradio wave irradiation detecting coil 102 and the radio wave absorptionmeasuring equipment 103. That is, with the existence of radio waveabsorption when a radio wave which is peculiar to a detecting object inthe article to be inspected such as a plastic bomb containing hexogen asa principal component is generated by the generating unit 1 andirradiated to the article to be inspected 109 using the irradiationdetecting coil 102, it is possible to detect whether hexogen iscontained in the article to be inspected 109 and further to conjecturethe content from the degree of the absorption intensity thereof. If thefrequency of the radio wave generated by the radio wave generating unit101 is set to the radio wave frequency peculiar to an explosivedangerous article such as trinitrotoluene (TNT) and potassium chlorateand above-described operation is performed repeatedly, it is possible todetect the existence and the content of hexogen, TNT and potassiumchlorate, etc. As it is apparent from above-described explanation,according to the present invention, not only the configuration of thedangerous article contained in the article to be inspected, but also thematerial property and the composition thereof can be detectedcollectively. Therefore, there is such an effect that explosivedangerous articles composed of an organic substance or an inorganicsubstance in a liquid form, a powder form and a plastic form that havebeen liable to be overlooked with a conventional X-ray transmitting typeinspection apparatus can be detected without omission.

In the present embodiment, the radio wave irradiation detecting coil 102is disposed on the article to be inspected 109 which is located in aspace put between the X-ray transmitting slit 105 and the X-raydetecting sensor 107, but it is needless to say that quite the sameeffect is obtainable when said article to be inspected 109 is positionedinside the irradiation detecting coil 102.

Further, in the X-ray transmitting detection apparatus, the X-raydetecting sensor 107 is disposed in a vertical direction with respect tothe article to be inspected 109, but it is a matter of course that theX-ray transmitting slit 105 and the X-ray detecting sensor 107 may bearranged in any direction with respect to said article to be inspected109.

Furthermore, it goes without saying that similar effects as the presentinvention are obtainable even when said radio wave irradiationinspection apparatus are not incorporated into said X-ray transmittingdetection units, but installed totally independent individually.

Moreover, in the present embodiment, an X-ray transmitted image of thearticle to be inspected 109 is obtained and utilized as X-rayinformation by using an X-ray detecting sensor 107 and the monitor 108,but fluorescence X-ray information generated in the article to beinspected 109 when X-ray is irradiated to the article to be inspected109 can also be used as X-ray information in place of abovesaid X-raytransmitted image. In this case, element information on the materialcontained in said article to be inspected 109 is utilized.

The basic operation of the present embodiment has been explained asdescribed above, but practical inspection steps of procedure on thedangerous article in the present embodiment will be described in thenext place. First, the article to be inspected 109 is carried to theinspection space between the X-ray transmitting slit 105 and the X-raydetecting sensor 107 from the waiting position by means of the jig 106for moving the article to be inspected. A belt conveyor and the like arerecommended for said moving jig 106. Since the visual field of the X-raydetecting sensor 107 is limited, the article to be inspected 109 ismoved gradually by the moving jig 106 so that respective portions of thearticle to be inspected 109 in the visual field of the X-ray detectingsensor 107 in every nock and corner. Since an X-ray and a radio wave areincoherent each other, the fluoroscopic inspection and the detection ofthe existence of radio wave are performed at the same time. That is,while a certain part of the article to be inspected 109 is beinginspected by fluoroscopy, a radio wave peculiar to the dangerous articleis irradiated at the same time. when a metallic dangerous article isdisplayed on the monitor 108, inspection is sustained immediately, andthe article to be inspected 109 is moved to the location for openinginspection by the moving jig 106. In case a clear fluoroscopic image bya metallic dangerous article does not appear on the monitor 108, presetabsorbing radio waves peculiar to explosive dangerous articles such ashexogen, TNT and chloriate are generated successively by the radio wavegenerating unit 101, and irradiated by the radio wave irradiating coil102, and the existence of absorption thereof is detected by the radiowave absorption detecting unit 103. In particular, when an unclear imagewhich is conceived to be produced by an organic compound powder and thelike is displayed on the monitor 8, it is desirable to device to doublethe irradiating radio wave intensity as compared with an ordinaryinspection and so on. If the whole preset absorption radio waveabsorbing band peculiar to an explosive dangerous article is swept andsuch radio wave absorption is not detected at all by the radio waveabsorption detecting unit 103, the article to be inspected 109 is movedby the moving jig 106 and above-described operation is repeated afteraltering inspection positions. Observation of images by the monitor 108has been made visually, but automation thereof is also easy. Automationmay be effected as follows. A threshold concentration Dl correspondingto metal and a threshold concentration D2 corresponding to organiccompound are set to the variable concentration of the fluoroscopicdetecting monitor 108, respectively. It may be judged that, when theX-ray transmitting concentration at the inspecting position on themonitor 108 of the article to be inspected 109 exceeds the thresholdconcentration Dl, a metallic dangerous article exists, and when theX-ray transmitting concentration is at the threshold concentration D2 orhigher and at the threshold concentration Dl or lower, an organiccompound powder exists. Further, since the output of the radio waveabsorption measuring equipment 103 is presented in an ON-OFF mannerconcerning radio wave absorption, it is quite easy to judge theexistence of hexogen, TNT, chlorate and the like. That is, it is onlyrequired for automation to add a monitor image concentration judgingunit, an output judging unit of the radio wave absorption measuringequipment 103, and an automated control circuit which judges the resultsof judgement of these both judging units synthetically and controlsmoving mechanism drive of the moving jig 106 to the ninth embodimentshown in FIG. 10.

Embodiment 10

Next, tenth embodiment of the present invention will be explained withreference to FIG. 11. In the tenth embodiment, radio wave irradiatingcoils 121, 122, 123 and 124 each in a signal layer spiral form havingdifferent maximum diameter dimension are arranged above the article tobe inspected 109, respectively. A radio wave generated by the radio wavegenerating unit 101 is distributed and supplied successively toirradiating coils 121, 122, 123 and 124 by a power switch circuit 110,and the existence and the intensity of radio wave absorption ofrespective coils are detected by the radio wave absorption measuringequipment 103 successively through a signal switch circuit 111. It mayalso be arranged that radio waves are supplied to respective irradiatingcoils at the same time and detection of radio wave absorption is madefor respective coils by a plurality of radio wave absorption measuringequipments corresponding to respective coils. The effective carry-overdistance of the radio wave irradiated from a spiral irradiating coil isa distance about the radius of the irradiating coil. Since radio waveirradiating coils 121, 122, 123 and 124 having different maximumdiameters are arranged on the article to be inspected 109 in the presentembodiment, it is possible to detect the depth of the location where thedangerous article is located in the article to be inspected 109. Forexample, when there is no radio wave absorption by hexogen with a coilhaving a small coil radius r₁ and there is radio wave absorption byhexogen with a coil having a large coil radius r₂, it is found that anexplosive dangerous article composed of hexogen exists at a location ofa distance r (r₁ <r<r₂) in the depth direciton from the top in thearticle to be inspected 109. Since the location of the dangerous articlein the article to be inspected 109 can be specified as described above,there is such an effect that opening inspection and removal of thedangerous article on the article to be inspected 109 can be performed ina short period of time, thereby to increase the efficiency ininspection. The radio wave irradiating coils are arranged above thearticle to be inspected 109 in the present embodiment, but there is nodifference in obtainable effects when the radio wave irradiating coilsare arranged in the side direction or in the bottom direction of thearticle to be inspected 109 other than the foregoing. Further, exactlythe same effects are obtainable when a multilayer coil is used in placeof the single layer spiral irradiating coil.

Embodiment 11

Next, an eleventh embodiment of the present invention will be explainedwith reference to FIG. 12. In the present embodiment, spiral coilpatterns 131, 132 and 133 are provided above a flexible insulating film136, and these are used as radio wave irradiation detecting coils.Further, the flexible insulating film 136 is held by an arm 134 which isable to hold and move the film, and can be deformed into anyconfiguration. In the actual operation, the arm 134 is controlled by anarm movement control unit 135 so as to move and deform the film. Theconcrete movement and deformation of said flexible insulating film 136are controlled by the arm movement control unit 135 so that theexistence of radio wave absorption at all portions in the article to beinspected 109 depending on the geometry of the article to be inspected109. Accordingly, spiral coil patterns 131, 132 and 133 are varied indimension similarly to abovesaid embodiment, and a deformable wiringcable such as a very thin coaxial cable is used for wirings 137 whichconnect an inptu system consisting of the radio wave generating unit 101and the power switch circuit 110 and an output system consisting of thesignal switch circuit and the radio wave absorption measuring equipment103 with the flexible insulating film 136. According to the presentembodiment, since the radio wave irradiation detecting spiral coilpatterns 131, 132 and 133 may be held by adhering to any surface of thearticle to be inspected 109, there is such an effect that inspection ofthe aritcle to be inspected 109 having a special configuration can beperformed easily. Further, since said coils may be adhered to thearticle to be inspected, only small irradiating radio wave power isrequired, thus also providing such a secondary effect that the dimensionof the radio wave generating unit 101 may be made small.

In respective embodiments described above, it is possible to utilizenuclear quadrupole resonance absorption of the explosive dangerousarticles as radio wave absorption peculiar to the explosive dangerousarticles contained in the article to be inspected 109. For example, itis only required to detect chlorine 35 nucleus resonance absorption tothe frequency of 28.1 MHz against a power bomb composed of potassiumchlorate KClO₃ and nitrogen 14 nucleus resonance absorption at thefrequency in the vicinity of 0.8 MHz, 0.9 MHz and 1.1 MHz against TNT.Also, nitrogen 14 nucleus resonance absorption originated by a nitrogroup may be observed similarly to TNT against a plastic bomb containinghexogen as the principal component thereof. In the case of a plasticbomb, however, hexogen is kneaded with rubber form binder and nuclearquadrupole resonance absorption originated by a nitro group is madewider in width. Accordingly, the existence of radio wave absorption hasto be checked in a wide range of frequency band covering 0.5 MHz to 2MHz.

Embodiment 12

Next, an embodiment of a radio wave generating portion, a radio waveirradiating portion and a radio wave absorption detecting portion whennuclear quadrupole resonance is selected as radio wave absorption willbe explained with reference to FIG. 13. In a twelfth embodiment shown inFIG. 13, the portion consisting of a frequency synthesizer 141, a pulsegate 142, a power amplifier 143 and a matching circuit 144 correspondsto the radio wave generating unit 101 in the ninth through informal theeleventh embodiments. A trimmer capacitor 145 attendant to theirradiation detecting coil 102 and a capacitor 146 forming a tuningcircuit together with the irradiation detecting coil 102 and serve forinjecting ratio wave power into the article to be inspected 109efficiently. Therefore, abovesaid trimmer capacitor 145 and capacitor146 may be regarded as a part of the irradiation detecting coil 102.Next, a portion consisting of a damper circuit 147, a preamplifier 148,a phase detector 149, a video amplifier 150 and a integrating adder 151corresponds to the radio wave absorption measuring equipment 103 in saidninth to eleventh embodiments. Now, a radio wave corresponding tonuclear quadrupole resonance absorption of a specific dangerous articlewhich has been set by the frequency synthesizer 141 is pulse-modulatedby the pulse gate 142. The pulse width, the pulse creation cycling timeand so forth can be set optionally by the controller 140. Then,, thisradio wave which has been made into a pulse form is amplified by thepower amplifier 143 and is irradiated to the article to be inspected 109by the irradiation detecting coil 102 after the matching circuit 144.The damper circuit 147 act to protect the radio wave absorptionmeasuring equipment portion against high electric power and to have afeeble nuclear quadrupole resonance signal pass without attenuation.When a specific dangerous article is contained in said article to beinspected 109, its nuclear quadrupole resonance is produced and aresonance absorption signal is generated in the irradiation detectingcoil 102. After said response absorption signal is converted into alow-frequency signal by the preamplifier 148 and the phase detector 149,it is amplified lastly by the video amplifier 150. Furthermore, in orderto improve the S/N ratio, noise component is removed by using theintegrating adder 151 in the present embodiment. Through above-describedprocedures, the nuclear quadrupole resonance signal is converted into alow-frequency periodic damping type signal. Because of such a reason,said signal is called free induction decay.

The existence and the intensity of nuclear quadrupole resonance areobserved using a CRT 152. Since nuclear quadrupole resonance absorptinois observed using a high power radio wave pulse in the presentembodiment, there is no waste of time due to frequency sweep as comparedwith, for example, a continuous detection method composed of frequencysweep, frequency modulation, phase detection and so forth of acontinuous radio wave. Thus, such an effect is obtained that the articleto be inspected 109 can be inspected in a short period of time. In thepresent embodiment, a single radio wave irradiation detecting coil 102is arranged above the article to be inspected 109, which is theconstruction shown in the ninth embodiment. However, in the constructionshown in the tenth and eleventh embodiments in which a plurality ofcoils are arranged, the radio wave generating unit and the radio waveabsorption measuring equipment described in the present invention mayalso be employed exactly in the similar manner, and similar effects areobtainable. In the next place, the result of detecting nuclearquadrupole resonance of chlorine 35 nucleus of potassium chlorate in asuit case with the construction of the present embodiment is shown inFIG. 14. A three folded spiral coil having a radius of 15 cm is employedfor the radio wave irradiation detecting coil 102. Other settingconditions are as follows. The set frequency f by the frequencysynthesizer 141: f=28.110 MHz. On time width τ of the pulse gate 142:τ=10 μsec. Radio wave output P after power amplification: P=3 KW. Radiowave pulse irradiation cycling period K: K=0.5 sec/time. Adding numberof times S by the integrating adder 151: S=10 times. Suit casedimensions: 1 m long×50 cm wide×25 cm thick. Since potassium chlorate ispowder, the same which is sealed in a paper box having content volume of250 cm³ (5 cm×5 cm×10 cm) was supposed to be an explosive dangerousarticle. The irradiation detecting coil 102 and the imaginary explosivedangerous article are made apart from each other by about 15 cm. Thisdistance is a length corresponding to the radius of the spiralirradation detecting coil 102, which, therefore, corresponds to thedetection limit distance. The free induction decay signal 160 shown inFIG. 14 was observed with the S/N ratio at about 150, and the inspectiontime required for the above was as shown as 5 seconds. It is realizedfrom above-descrbied results that the dangerous article inspectionapparatus is of practical use sufficiently.

Embodiment 13

A thirteenth embodiment of the present invention will be explained withreference to FIG. 15. In FIG. 15, the X-ray inpsection apparatus portionconsisting of the X-ray generarting unit 104, the X-ray transmittingslit 105, the X-ray detecting sensor 107 and the monitor 108 similarlyto FIG. 13 which is shown as twelfth embodiment is omitted for the sakeof simplifying the drawing. In the embodiment shown in FIG. 15, a staticmagnetic field generating coil 170, an gradient magnetic fieldgenerating coil 171, an gradient magnetic field power source 172 and astatic magnetic field power source 173 are added to the composition ofthe embodiment shown in FIG. 13, respectively. In the presentembodiment, the existence of a specific dangerous article is detected bythe existence of nuclear magnetic resonance radio wave absorption of thedangerous article contained in the article to be inspected 109. In orderto make the explanation of the present embodiment easier to understand,it is assumed that a TNT bomb packed in a case is hidden in the articleto be inspected 109 as a dangerous article and that nuclear magneticresonance radio wave absorption of hydrogen 1 nucleus of the TNT bomb isobserved in the following explanation. First of all, a uniform staticmagnetic field H_(O) is generated over the whole article to be inspected109 by the static magnetic field power source 173. The nuclear magneticresonance absorption radio wave frequency f_(H) of hydrogen 1 nucleus ofthe TNT bomb is determined principally by the static magnetic fieldH_(O). The existence of the TNT bomb can be detected by having a radiowave having a frequency f_(H) generated by the frequency synthesizer141, irradiating the radio wave having the frequency f_(H) to thearticle to be inspected 109 using the irradiation detecting coil 102 inthe similar manner as the twelfth embodiment shown in FIG. 13, andjudging the existence of the induced nuclear magnetic resonanceabsorption signal of hydrogen 1 nucleus of the TNT bomb on the CRT 152.In this case, however, only the fact that TNT exists in the article tobe inspected 109 is found, and the position thereof cannot be located.Such a problem can be solved by superposing an gradient magnetic fieldHg (Z) which increases or decreases spacially by the gradient magneticfield generating coil 171 and the gradient magnetic field power source172 to H_(O). Here, Z shows, for example, a Z-axis coordinate fixed in alaboratory. When it is assumed that TNT bombs are located at positionsZ=Z₁, and Z=Z₂, respectively, magnetic fields at respective TNT bombpositions are different due to superposition of the gradient magneticfield Hg (Z). Therefore, the frequencies of nuclear magnetic resonancesignals of hydrogen 1 nuclei originated in respective TNT bombs aredifferent to be f₁ and f₂. It is possible to compute the positionsconversely from the difference of frequencies f₁ and f₂. To be concrete,the radio wave generated by the synthesizer 141 is pulse-modulated bythe pulse gate 142 so that the spectral distribution thereof covers bothf₁ and f₂, and irradiated to the article to be inspected 109 by theirradiation detecting coil 102 after power amplification. The nuclearmagnetic resonance signals of induced frequencies f₁ and f₂ areamplified, respectively, lastly fed to a Fourier transform unit 174, andthen displayed on the CRT 152. It is possible to detect the magneticfield intensities of respective positions, that is, the positionsthemselves from the frequencies f₁ and f₂. According to the presentembodiment, there is such an effect that the dangerous artricle in saidarticle to be inspected 109 can be inspected in every nook and cornerwithout moving the irradiation detecting coil 102 with respect to thearticle to be inspected 109.

As a more important effect, such a point may be mentioned that anexplosive dangerous article can be detected without distinction betweena liquid and a solid body. This is not included in nuclear quadrupoleresonance radio wave absorption used in the twelfth embodiment shown inFIG. 13. This is because of the fact that resonance absorption of asubstance having no structural regularity at all such as a liquid cannotbe detected by nuclear quadrupole resonance. On the other hand, when anexplosive dangerous article is held in a metallic container, a radiowave is shielded by said metallic container. Therefore, it is difficultto detect the dangerous article by the existence of nuclear magneticresonance absorption. This is similar to the case of the twelfthembodiment utilizing nuclear quadrupole resonance absorption. In thiscase, since the metallic case can be detected easily by means of afluoroscopic inspection apparatus, the effectiveness of the dangerousarticle inspection apparatus of the present invention will never bespoiled at all.

In the above-described explanation of the embodiments of the presentinvention, nuclear magnetic resonance absorption and nuclear quadrupoleresonance absorption that are peculiar to a dangerous article have beenutilized as radio wave absorption, but a dielectric relaxation lossphenomenon can also be utilized other than the above. That is,dielectric loss is produced when a dangerous article has dipole moment,and the loss profile on the frequency is peculiar to the dangerousarticle. Utilization of dielectric relaxation loss is particularlyeffective in case the dangerous article does neither show nuclearmagnetic resonance absorption nor nuclear quadrupole absorption. Theapparatuses shown in the ninth through the eleventh embodiments may beutilized for the inspection apparatus.

According to the present invention, an atomic nucleus which generatesnuclear quadrupole resonance included in an explosive dangerous articleis detected, and moreover, detection is made with a resonance frequencywhich is different depending on the type of the explosive substance.Thus, there are remarkable effects in that it is possible to detectwhether an explosive dangerous article is included in an article to beinspected or not, which has been impossible by a conventional X-rayinspection apparatus, and further in identifying the type of theexplosive dangerous article.

In particular, a plastic explosive compound being deformable into anyconfiguration, it has been difficult to detect it by recognition ofconfiguration thereof. According to the present invention, however, theexplosive compound can be detected irrespective of configuration.Therefore, the present invention is very effective in detection of aplastic explosive compound.

Further, since a radio wave transmits through a bag and clothes in mostcases, it is not required to open the bag or have clothes put on and offexpressly, thereby to inspect a dangerous article quickly.

Furthermore, a dangerous article inspection apparatus of the presentinvention is provided with a radio wave generating unit, a radio waveirradiation detecting coil and a radio wave absorption measuringequipment in a dangerous article inspection apparatus provided with anX-ray generating unit, an X-ray transmitting slit, an X-ray detectingsensor and an X-ray inspection apparatus, and X-ray information of thearticle to be inspected from said X-ray inspection apparatus andspecific danger information in the article to be inspected by theexistence and the degree of specific radio wave absorption are obtained,thereby to detect configuration, material property and composition, etc.of the dangerous article synthetically. Therefore, it is possible toinspect configuration, material property and composition of the insideof the article to be inspected including explosive dangerous substancescontaining organic substances and inorganic substances in liquid, powderor plastic form and further metallic small weapons synthetically in anon-destructive mannner, thus providing such an effect that dangerousarticle can be detected without omission.

We claim:
 1. A detecting method for a specific substance, comprising:astep of bringing an article to be inspected to a predetermined position;a step of irradiating an electromagnetic wave having energy in thevicinity of transition energy between spin states of an atomic nucleusapplied with energy splitting due to electrostatic interaction, betweensaid atomic nucleus in the specific substance and an electric field inthe substance which is peculiar to said specific substance is irradiatedto the article to be inspected located at the predetermined position,thereby detecting transition between said spin states; and a step ofdetecting the existence of said specific substance in said article to beinspected.
 2. A detecting method according to claim 1, wherein saidenergy splitting is caused by electrostatic interaction between electricquadrupole moment of said atomic nucleus and gradient of an electricfield in said substance.
 3. A detecting method according to claim 1,wherein said electromagnetic wave is irradiated steadily to saidpredetermined position.
 4. A detecting method according to claim 3,wherein the frequency of said electromagnetic wave is set to a nuclearquadrupole resonance frequency of nitrogen 14 nucleus or chlorine 35nucleus in an explosive substance, and the existence of said explosivesubstance in said article to be inspected is detected.
 5. A detectingmethod according to claim 1, wherein said irradiation detecting stepfurther includes a modulation step applying either frequency modulationor amplitude modulation to said electromagnetic wave.
 6. A detectingmethod according to claim 1, wherein said irradiation detecting stepfurther includes a step of applying frequency modulation with alow-frequency signal to said electromagnetic wave within a frequencyrange including nuclear quadrupole resonance frequency of nitrogen 14nucleus or chlorine 35 nucleus in an explosive substance and a step ofdetecting the existence of said explosive substance in said article tobe inspected based on a low-frequency demodulation signal.
 7. Adetecting method according to claim 1, wherein said irradiationdetecting step further includes a step of setting the frequency of saidelectromagnetic wave to nuclear quadrupole resonance frequency ofnitrogen 14 nucleus or chlorine 35 nucleus in an explosive substance, astep of modulating the amplitude of said electromagnetic wave with alow-frequency signal, and a step of detecting the existence of saidspecific substance in said article to be inspected.
 8. A detectingmethod according to claim 1, wherein said irradiation detecting stepfurther includes a step in which said electromagnetic wave irradiatesone of a single high-frequency pulse and a plurality of high-frequencypulses adjusted in time and/or in phase.
 9. A detecting method accordingto claim 8, wherein said irradiation detecting step further includes astep of detecting attenuation or recovery of an induced electromagneticwave generated in said article to be inspected by said electromagneticwave after said supplied electromagnetic wave is cut off.
 10. Adetecting method according to claim 1, wherein transition between saidspin states is detected as absorption of said supplied electromagneticwave in said article to be inspected.
 11. A detecting method accordingto claim 1, wherein transition between said spin states is detected asphase shift of the induced electromagnetic wave generated in saidarticle to be inspected by said supplied electromagnetic wave withrespect to said supplied electromagnetic wave.
 12. A detecting methodaccording to claim 1, wherein transition between said spin states isdetected by detecting the variation of nuclear magnetic resonance signalof one atomic nucleus caused by transfer of energy absorbed by the otheratomic nucleus by means of transition between spin states attendant uponthe supply of said electromagnetic wave to said one atomic nucleusapplied with Zeeman splitting which is close to said other atomicnucleus.
 13. A detecting apparatus for a specific substance,comprising:a probe coil for emitting an electromagnetic wave fordetection to an article to be inspected; an oscillator and detectorconnected to said probe coil and generating and detecting anelectromagnetic wave; frequency control means for setting saidelectro-magnetic wave to a nuclear quadrupole resonance frequency ofconstituent atom of an object of detection under a chemical structurepeculiar to said object of detection; means for detecting variation ofconductance of a tuning circuit of said oscillator and detector; andmeans for displaying variation of conductance of said tuning circuitwhen setting is made to said resonance frequency.
 14. A detectingapparatus according to claim 13, wherein said probe coil is formedmovable around said article to be inspected.
 15. A detecting apparatusaccording to claim 13, wherein said probe coil is a coil composed ofsingle layer or multilayer sprial winding.
 16. A specific substancedetecting apparatus comprising:an X-ray inspection apparatus includingan X-ray generating unit, means for irradiating an X-ray from said X-raygenerating unit to an article to be inspected, an X-ray detecting sensorfor detecting an X-ray which has transmitted through said article to beinspected, and a monitor informing of the result detected by saidsensor; and a radio wave absorption measuring equipment including aradio wave generating unit, a radio wave irradiation detecting coil forirradiation the radio wave form said generating unit to said article tobe inspected, and means for detecting absorption of said radio wave by aspecific substance in said article to be inspected; the specificsubstance in the article to be inspected being detected by X-rayinformation on the article to be inspected obtained from said X-rayinspection apparatus and the existence and the degree of specific radiowave absorption obtained from said radio wave absorption measuringequipment.
 17. A detecting apparatus according to claim 16, wherein saidX-ray inspection apparatus further includes means for displaying anX-ray transmitted image of the article to be inspected so as to detectthe configuration of the specific substance.
 18. A dangerous articledetecting apparatus according to claim 16, wherein said radio waveirradiation detecting coils are coils composed of a signal layer ormultilayer spiral winding.
 19. A detecting apparatus according to claim16, wherein said radio wave irradiation detecting coil is provided witha plurality of coils each having different maximum diameters arrangedseparately in space and means for using any one of them or anycombination thereof selectively.
 20. A detecting apparatus according toclaim 16, wherein said specific radio wave absorption measuringequipment is means for measuring nuclear magnetic resonance absorptionof a specific substance in said article to be inspected.
 21. A detectingapparatus according to claim 16, wherein said specific radio waveabsorption measuring equipment is an equipment for measuring nuclearquadrupole resonance absorption of a specific substance in said articleto be inspected.
 22. A detecting apparatus according to claim 16,wherein said specific radio wave absorption measuring equipment is anequipment for measuring dielectric relaxation absorption of a specificsubstance in said article to be inspected.
 23. A dangerous articleinspection apparatus according to claim 20, wherein said nuclearmagnetic resonance absorption measuring equipment is an equipment formeasuring nuclear magnetic resonance absorption of at least one ofhydrogen 1 nucleus, carbon 13 nucleus, nitrogen 14 nucleus, nitrogen 15nucleus, chlorine 35 nucleus and chlorine 37 nucleus.
 24. A dangerousarticle inspection apparatus according to claim 21, wherein said nuclearquadrupole resonance absorption measuring equipemnt is an equipment formeasuring nuclear quadrupole resonance absorption of at least one ofnitrogen 14 nucleus, chlorine 35 nucleus and chlorine 37 nucleus.
 25. Adangerous article inspection apparatus according to claim 16, whereinsaid radio wave irradiation detecting coil has such a construction thatthe position thereof may be held under or moved to closely adheredstate, separated state or intermediate state therebetween.
 26. Adangerous article inspection apparatus according to claim 18, whereinsaid radio wave irradiation coils are formed on a flexible insulatingfilm.